1. Field of the Invention
This invention relates to new and useful improvements in a portable teaching display unit and more particularly seeks to provide a convenient case that can be readily converted from a carrying case for all the components to a display unit that is an attractive, desirable teaching mechanism for individual users and specially embodies in such a unit a laminated structure providing predetermined areas of conductance and insulation whereby a circuit can be closed at conductance areas to light a bulb, ring a bell, etc. to indicate correct answers to a problem, but where the remaining areas of insulation will not close a circuit to provide such a signal.
2. Description of Prior Art
Many games or teaching units have involved a question-answer probe that closes an electrical circuit with a light therein on selection of a correct answer. Most of these have printed circuit systems or other complex and expensive electrical systems, as noted for example in U.S. Pat. Nos. 2,586,710, 2,889,634, 3,057,082 and 3,139,688. The Greenspan Pat. No. 3,316,660 has an aluminum foil laminated between two paper sheets, the paper sheets being perforated for an electrical probe to close a circuit through the metal foil conducting medium. To avoid closing the circuit at incorrect answers, the foil at those points is covered by a dielectric coating. The foil is associated with and laminated between two specified sheets and is not useable for other sheets.